Figure 1

survival and A2B5 staining of oligodendrocytes following treatments with cytokines and corticosteroids. Phase contrast microphotographs as well as anti-A2B5 staining after three days in proliferation medium followed by 6 days in differentiation medium. Note, that after treatment of oligodendrocyte precursors with TNFα (10 ng/ml) and IFNγ (10 U/ml) for 48 h on 2–3 days in vitro (C) cells display mostly bipolar morphologies typical for progenitor cells, maintaining their A2B5 immunopositivity. Coapplication of dexamethasone during cytokine treatment (D) in the proliferation medium restored the extension of multipolar arborizations and the downregulation of A2B5 staining. (E) Average number of cells per field of view at culture day 9 (for every bar 25 fields of view from 12 coverslips of the control cultures and 4 coverslips of the corticosteroid treated cultures were counted). In both, control (left bars) and in cytokine-treated cells (right bars) corticosteroids caused a significant increase in the total number of cells surviving in culture. (F) Percentage of A2B5 positive cells at culture day 9. Note, that in control cells not treated with cytokines (left four bars) no significant effect of corticosteroids on the number of A2B5-positive cells was detected, whereas in cytokine-treated cultures the percentage of A2B5-positive cells was decreased by cotreatment with corticosteroids (CS: corticosterone, DC: deoxycorticosterone, D: dexamethasone, no corticosteroid treatment (-) * p < 0.05, ** p < 0.01, *** p < 0.001. For reasons of comparison the black bars in E and F are based on data published in [10], Figure 3B. Since cell counting was performed directly at the fluorescence microscope, fields of view were slightly larger than the photomicrographic frames shown. (G) Flow chart of the experimental design: After day 1 in proliferation medium, test cultures of oligodendrocyte precursors were treated for 48 hours with control proliferation medium or 10 U/ml IFN-γ and 10 ng/ml TNF-α in the presence or absence of glucocorticoids. The treatment was stopped by transferring the cells into differentiation medium. To judge long-term effects of treatments of precursor cells on subsequent differentiation most investigations were performed following 6 days in differentiation medium.